Newsgroups: comp.parallel.pvm From: Don Dossa Subject: Re: fddi vs fast ethernet (follow-up) Organization: Digital Equipment Corporation Date: Mon, 15 Sep 1997 09:48:33 -0400 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <341D3CB1.6201@eng.pko.dec.com> Jude, There are a few other things to think about before you do anything to your workstation cluster. 1. Do not *even* think about getting a switch. This makes absolutely no sense at all for anything less than 4 systems. Think about it. What does a switch do? It lets multiple systems communicate simultaneously. And what system will the third system talk to when the other two are busy? 2. William Rankin of Duke commented correctly that more CPU time is spent handling the network adapter than actually moving bits on the wire. If your typical message is only a few hundres bytes, then you wont see a performance gain switching from 10 Mb/s to 100 Mb/s. 3. What else is on your network? If these 3 systems are on a public network, then the traffic caused by other systems may be a source of a performance problem. Are you using a file server? Do you think there is any disk IO going on during your runs? What network is that traffic travelling on? Your biggest performance gain and also lowest cost might be to purchase 3 10 Mb/s Ethernet cards and build a private network between the three systems. If you are sending long messages, 3 100Mb/s controllers might be worth it. Regards, Dr. Don Dossa Workstation Engineering Digital Equipment Corp.